Optimizing the production of metastable calcium atoms in a magneto-optical trap

We investigate the production of long-lived metastable (4 P-3(2)) calcium atoms in a magneto-optical trap (MOT) operating on the 4 S-1(0) --> 4 P-1(1) transition at 423 nm. For excited 4 1 PI atoms a weak decay channel into the triplet states 4 P-3(2) and 4 P-3(1) exists via the 3 D-1(2) state. The undesired 4 P-3(1) atoms decay back to the ground state within 0.4 ms and can be fully recaptured if the illuminated trap volume is sufficiently large. We obtain a flux of above 10(10) atoms/s into the 4 P-3(2) state. We rind that our MOT lifetime of 23 ms is mainly limited by this loss channel, and thus the 4 P-3(2) production is not hampered by inelastic collisions. If we close the loss channel by repumping the 3 D-1(2) atoms with a 671 nm laser back into the MOT cycling transition, a non-exponential 72 ms trap decay is observed, indicating the presence of inelastic two-body collisions between 4 S-1(0) and 4 P-1(1) atoms.